SQL Server Magazine

DPM 2007
DPM 2007, see Web Figure 3, is the latest enhancement to Microsoft’s near-CDP application and system recovery suite. The product has specific support for a variety of Volume Shadow Copy Service (VSS)-supporting applications, including Windows Server 2008, Windows Server 2003, SQL Server 2005, SQL Server 2000, Exchange Server 2007, Exchange Server 2003, Windows SharePoint Services (WSS) 3.0, Microsoft Office SharePoint Server 2007, and Microsoft Virtual Server 2005. DPM also supports protection of XP- and Windows Vista-based (except Home editions) shares. In all cases, DPM supports protection of both 32-bit (x86) and x64 versions, with no support for IA-64 environments. DPM support for non-Microsoft VSS-enabled applications is possible, if the application vendor provides the necessary VSS interface definition.

DPM’s architecture is easy to understand. The product runs on a Server 2003 or Windows Storage Server 2003-based system, where it maintains replicas of protected data. A DPM agent runs on all protected systems and copies protected data to the DPM server at user-specified times or intervals in two ways: using what DPM calls an Express Full Backup, to create a full recovery point, and using what DPM calls Synchronization, to create an incremental backup. Express Full Backup uses a data block-oriented copy to create a replica of the protected object (e.g., a database, Exchange storage group, or Virtual Hard Disk—VHD) on one of DPM’s storage disks. The agent tracks new and changed data blocks within protected objects on the volume and sends only those blocks to the DPM server when subsequent Express Full Backups are run. Synchronization, the creation of incremental recovery points, is available only when the protected application supports incremental backup. In the case of SQL Server, DPM lets you specify a Synchronization frequency only when the protected database maintains a transaction log file. For simple recovery model databases, only Express Full Backups create a recovery point. The DPM agent makes use of the VSS writer’s ability to quiesce application activity and produce a snapshot of the data object in a stable, usable state. Once the data is preserved at the DPM server, the agent deletes the snapshot, freeing its storage. Similarly, when recreating a Full Express Backup replica after an outage, the agent compares the blocks of the existing replica on the DPM server to a snapshot of the current data object on the protected system and sends only the differences. You can schedule Express Full Backups to occur as frequently as every 30 minutes by selecting the days of the week and the times of day DPM will perform the backup. You schedule Synchronization by selecting an interval of as little as 15 minutes. Although the incremental backup provided by Synchronization lets you recover changes that occur after the prior Express Full Backup, recovery is often faster using a recent Express Full Backup, with fewer incremental recovery points (i.e., log backups) to apply.

The licensing model is, for once, simple. You buy a license for each DPM server, a Standard Server license for each system requiring only file system and system state protection, and an Enterprise Server license for each protected system requiring application or bare-metal restore protection. Despite its name, the Standard Server license is applicable to workstations and other supported clients that need only file system and system state protection.

DPM has several prerequisites. Currently, all systems require VSS-related hotfixes. The DPM server requires the Windows PowerShell scripting environment. DPM also requires an instance of SQL Server, which it installs on the local system by default. Once the prerequisites were met on my system, DPM installed quickly.

Microsoft provides two user interfaces: the DPM Administrator Console, which is DPM’s primary management GUI; and the Management Shell, a command-line interface that supports scripted operations. The Administrator Console, which Figure 3 shows, is well designed. I found it very easy to navigate and simple to use.

DPM stores protected data within its storage pool, which consists of one or more physical disks dedicated to DPM. After installing DPM, adding at least one physical disk to the storage pool is the first configuration task. DPM allocates volumes on storage pool disks for each protected data object where it stores replicas and Synchronization recovery points, extending volumes when necessary.

The next implementation steps require installing the DPM agent on systems you want to protect, then defining protection groups. The Administrator Console makes both steps easy. Selecting Install from the Administrator Console’s Management tab starts the agent installation wizard, which installs the agent and optionally restarts each system after letting you enter the necessary administrative credentials and selecting target systems. Agent installation on my test SQL Server system took only a few minutes. Similarly, selecting Create Protection Group from the Protection tab started a wizard to guide me through the few necessary steps. The wizard displayed all systems running the agent in an Explorer-like view, letting me expand a system to display shares, volumes and—in my case—SQL Server machines, as Figure 4 shows. Simply click to select an item, and it displays in the Selected Members pane. Subsequent wizard screens let you select preset times to perform Express Full Backups for group members, as well as select how often to use Synchronization for incremental backups. When the DPM server has access to a tape device, you can choose to write protected data directly to tape, and to define long-term data retention policies. Because creating an initial data replica of large data objects over a network can take much longer than creating it locally, DPM gives you both options when you create a protection group.

I discovered one inconvenient feature. I choose to modify a protection group, adding two file directories comprising about 20MB of data. Even though my storage pool had more than 13GB of available space, the Administrator Console reported insufficient space for the protection group. After I freed more space by deleting a protection group, DPM allocated 15GB of disk space for the 20MB of file data. I suspect that in circumstances like this—when your data structures’ growth and change behavior doesn’t match DPM’s built-in assumptions—administrators would prefer to use DPM’s support for custom storage volumes that let you, rather than DPM, manage the space allocations. DPM lets you specify a preallocated, custom storage volume only when you add a member to a protection group.

Data recovery is also a simple, wizard-driven process. Clicking the Recovery tab displays a tree structure that includes all protected data objects, letting you select the recoverable object (e.g., a database, file directory, or file) and the recovery point. DPM allows you to direct the recovered data to its original location or another location. In the case of a SQL Server database, the alternatives include disk, tape, or another SQL Server system running the DPM Protection Agent. I tested all but the tape alternative to recover a SQL Server database, and the results were mostly as I expected. I recovered a selected Synchronization recovery point to the database’s original location, and the data in the resulting database was consistent with my expectations. Similarly, recovery to an alternative location while specifying a new database name resulted in an operational database. In the latter case, DPM renamed the database but didn’t rename the MDF and LDF files to be consistent with the new database name. DPM warned me and allowed me to select a new directory location for these files, so they wouldn’t overwrite the production files if I wanted to create the copy on the original database server. Restoring to a network folder resulted in an MDF and LDF file in the target folder. When selecting a recovery point, DPM lets you specify “latest” to select and restore data as of the most recent recovery point. When recovering protected Exchange data, DPM permits granular recovery down to the mailbox level.

The Monitoring tab lets you view the status of all DPM jobs, which implement protection tasks and recovery operations. Exceptional conditions are also reported on the Monitoring tab’s Alerts pane.

The Reporting tab lets you schedule and generate six types of reports in Web, PDF, and Microsoft Excel formats: Disk Utilization, Protection, Recovery, Status, Tape Management, and Tape Utilization. Disk Utilization, as the name implies, details disk usage and free space availability. The Protection report details available recovery points, and Recovery reports on the performance of recovery jobs during an interval. The Status report shows the activities related to each recovery point during a specified time period. The Tape Management report supports tape rotation, whereas the Tape Utilization report is organized to show where volumes are currently allocated.

By adding another DPM server you can easily configure offsite storage of protected data. To the “offsite” DPM server, the primary DPM server is just another resource you can protect, which lets you include just the recoverable data objects that you want to protect offsite in the offsite server’s protection groups.

Summary
System Center Data Protection Manager 2007
PROS: Broad support for Microsoft applications, and third-party VSS-enabled applications with vendor support; designed for ease of use—all tasks are wizard driven and easy to complete; clean integration of both disk and tape into short- and long-term protection policies let you easily implement data retention and recovery for the full life cycle of your data
CONS: DPM’s disk space allocation for storing protected data might not efficiently match your data’s growth and change patterns; however, there’s an option that lets you manage storage allocations yourself
RATING: 4
PRICE: $573 per DPM server; $426 per Enterprise Server management license; $155 per Standard Server management license
RECOMMENDATION: Small organizations will find DPM easy to incorporate into their protection strategy, and large organizations will appreciate the clean support for Microsoft applications. DPM 2007 is a well-designed near-CDP product that I recommend to all users of the key Microsoft applications that it supports.
CONTACT: Microsoft • 800-642-7676 • www.microsoft.com

TimeData
TimeSpring’s TimeData, see Web Figure 4, is a CDP solution for protecting files, Exchange data, and SQL Server databases. TimeData is a true CDP solution, allowing recovery to any point in time.

TimeData comprises several components. The key system is TimeData’s repository server, where TimeData stores protected data. TimeSpring recommends that this server have at least 2GB system memory when protecting one to three data servers, and at least 4GB when protecting four to eight data servers. TimeData stores protected data in its Event Log file and installs an instance of SQL Server 2005 (provided with a limited-use license) that TimeData uses to index the data in the Event Log file. To enhance performance, both the Event Log file and the TimeData database should be on separate disks, with system and paging files on other disks. The Event Log disk should be six to eight times the size of the data you’re protecting. TimeSpring recommends use of a separate, dedicated network for the transfer of data from protected servers to the repository server.

You install the TimeData Agent on servers whose data you want to protect—which TimeSpring calls Data Servers. TimeData supports protection of NTFS files (except TimeData and Windows system files), SQL Server 2005 (both x64 and x86 versions), SQL Server 2000, WSS 2.0, Exchange 2003, and Exchange 2000 Server, with limited support for Exchange 2007. Although the repository server must run an x86 version of Server 2003 or Windows 2000 Server, the agent is supported on both x86 and x64 versions of those OSs. The SharePoint agent is an exception, requiring an x86 OS. Protected data must reside on locally attached, SAN, or iSCSI storage.

I installed TimeData Data Server 2.7.1.344, according to the TimeData Planning and Installation Guide procedure. Installation of the repository server took the better part of an hour, with much of that time spent on SQL Server 2005 installation. Installing the agent on a SQL Server 2005 system took about 20 minutes. The agent queues data on its way to the repository using an Event Cache, which for performance reasons should be on its own disk on each data server.

You use the TimeSpring Management Console on the repository server to configure and manage TimeData. Remote management is possible only with the use of a remote desktop application.

Although the following discussion focuses on my testing with SQL Server, working with NTFS files and Exchange is similar. After installing the software, the next step is to create a content group—a named collection of files and data structures on a single data server that you want TimeData to protect. To give you some control over the granularity of potential restore points with SQL Server, TimeData lets you configure when it will create a new version, which is what TimeData calls a potential restore point. The alternatives are every time an application commits a transaction to the database; only when the commit for a named transaction or a database checkpoint commit occurs; or only when a database checkpoint occurs. I started with the default, named transactions only, when I created a content group for two databases on the single data server I had configured. Although a content group protects data from one server only, you can configure many content groups for any server. After I created the content group, TimeData began the initial backup of the databases I had configured.

For additional flexibility, including offsite backup, TimeData lets you configure a data server with more than one repository. Using the second repository server, you can import existing content groups from the data server, or create new content groups. Allowing different content groups from a single server to connect to different repositories lets you be selective about the data that occupies a WAN link, and lets you distribute the protection of large, active data servers between several repositories.

TimeData provides a lot of flexibility for recovering data. You start by using the TimeSpring Management Console, see Web Figure 5, to display and select a version of the database to work with. The console will display as many as 1,000 timestamped versions at a time, and it lets you filter by time range to help locate the desired version. After selecting a version to work with, you create a fixed time retrieval view of the content group, which TimeData adds to the console tree, as Figure 5 shows. Within the console, you can select a database from the view and have TimeData write it to another location on disk. TimeData also presents the files on the TimeData drive, a virtual disk drive on the repository server mapped by TimeData to a drive letter you specify at installation time. TimeData creates the virtual drive with a network share, letting you access the files across the network. I copied the database to a second SQL Server machine, attached it, and verified that the data it held was consistent with the recovery time I had selected.

One of TimeData’s benefits is its ability to run databases configured for simple recovery mode. Because the software can store data at each commit and checkpoint, it provides very granular recovery ability without the need to retain SQL Server transaction log data.

Working with Exchange data is similar. A fixed time retrieval view of a content group that protects an Exchange installation provides you with access to a point-in-time version of an Exchange EDB file. When you license TimeData for Exchange, TimeSpring provides a license to use Ontrack PowerControls and its ability to perform message-level restore operations from the offline EDB file.

Overall I found TimeData easy to install, configure, and use to retrieve point-in-time versions of data files. The fixed time retrieval view and the TimeData drive provide rapid access to point-in-time data across a network share. I discovered a limitation to the usefulness of the TimeData drive share when the number of characters in the path to a SQL Server MDF file was too long for remote access—I had to create a new share at the folder that contained the files I wanted to copy. TimeData’s ease of use ends with rapid access to the file. It lacks features to recover production databases to a point in time, leaving it up to you to use standard SQL Server database tools to work with the point-in-time database. On the plus side, its architecture seems well suited to a highly scalable implementation.

Summary
TimeData 2.7.1
PROS: Easy to implement and manage—the Management Console allows effective centralized configuration and management of all protected systems; architecture is very flexible and seems highly scalable; transaction-level recovery even for simple recovery model databases; includes tools for message-level restore when licensed for Exchange
CONS: Relatively heavy system memory and storage resource requirements; lacks integrated tools for recovery of protected applications—TimeData provides the point-in-time data, and you employ standard tools to use the data
RATING: 3.5
PRICE: Per server pricing: NTFS $1,295; SQL Server $3,995; Exchange starting at $3,995
RECOMMENDATION: This traditional CDP product focuses on providing easy access to point-in-time data. When TimeData is implemented as part of an application or disaster recovery plan, you must create your own procedures to apply the recovered data to your application or recovery environment. Use TimeData if its custom recovery methods fit your environment.

The Bottom Line
Each of these four products will find its niche. CA XOsoft WANSyncHA is an easy to implement high availability product, with a fast, effective data rewind feature. The SonicWALL CDP series of data protection appliances is easy to implement and simplifies restoring SQL Server databases to a point in time by automating the selection and use of the appropriate set of backup files. DPM offers the most complete support for Microsoft applications, near-CDP recovery points, and—except perhaps when it comes to managing disk utilization for protected data—ease of implementation and use. TimeData’s ability to quickly construct and make available on a network share a point-in-time view of a protected file or database, even for simple recovery model databases, will be attractive to many administrators.

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